The present invention relates, in general, to ultrasonic surgical devices and, more particularly, to a new ultrasonic surgical instrument and method including inactive tissue clamping surfaces positioned laterally on either side of a longitudinal ultrasonic blade.
Ultrasonic surgical instruments are continuing to gain acceptance with surgeons as a replacement for a variety of conventional surgical instruments. The advantages of a single instrument that uses ultrasonic energy for cutting, coagulating, or welding tissue is of great value to the surgical community. Applying ultrasonic vibrational energy to tissue is rapid, results in minimal trauma and bleeding, and is sometimes referred to as xe2x80x9cbloodless surgeryxe2x80x9d.
An elongated blade extends from the distal end of the ultrasonic surgical instrument and is ultrasonically vibrated to a resonance condition by a transducer assembly. Pressing the exposed vibrating blade against tissue transmits ultrasonic energy to the tissue. Due to the ultrasonic vibrations, a distal portion of the elongated blade oscillates rapidly in a proximal to distal manner relative to the longitudinal axis of the instrument. This rapid oscillation or proximal to distal movement of the elongated blade is known as excursion. Excursion is non-uniform along the exposed blade length, attaining a maximum at the distal end and decreasing toward the proximal portion of the exposed blade. Tissue effects are directly related to the excursion of the elongated blade, with the greatest tissue effects being obtained at or near to the distal end. Application of the distal end to tissue results in cavitation effects such as coagulation and emulsification, and the sides of the blade produce frictional effects such as coagulation and cutting.
Three elements control the tissue coagulation effects: pressure applied to the tissue by the active blade (i.e.: force), the amount of energy delivered to the tissue by the blade (i.e.: power), and the duration of the energy delivery (i.e.: time). Different tissue effects are obtained by varying these parameters and by using different portions of the elongated ultrasonic blade on tissue. Placing the side of the elongated blade against tissue produces a frictional interaction between the elongated blade member and the tissue. This frictional interaction creates heat within the tissue and coagulates tissue adjacent to the oscillating elongated blade. Continued application of energy to tissue (with the side of the blade) produces a tissue coagulation zone, which spreads away from the elongated blade producing an effect known as lateral thermal spread. Using the sides of the blade to cause lateral thermal spread has proven useful when hemostatically sealing vessels or welding portions of tissues together.
Clamping or compressing tissue together prior to the application of energy was found to facilitate the sealing and welding process. Good tissue welds are obtained by applying a combination of pressure and energy to a selected portion of tissue. First, tissue is clamped or compressed together into a desired tissue orientation and second, ultrasonic energy is applied to the compressed tissue to weld it together. Combining a clamping mechanism with the elongated blade ultrasonic instrument proved revolutionary with the surgical community.
One type of ultrasonic surgical instrument clamps tissue directly against the side of the elongated blade. This type of a clamp and coagulation instrument generally has a clamp arm that is moveable from a first position spaced away from the side of the blade to a second position clamped against the side of the elongated blade. Clamping tissue against the side of the elongated blade increases the transfer of energy to tissue and enhances tissue coagulation and cutting effects. Additionally, using the side of the elongated blade provides the surgeon with a large tissue bite. Examples of ultrasonic surgical instruments that clamp against the side of the blade are described in the U.S. Pat. No. 5,322,055 by Davison et al., and in a Japanese Laid-Open Patent Application (Kokai) No. 8-275951 by Mitsumasa Okada et al.
Another type of ultrasonic instrument uses the distal end of the elongated blade to cut, and has a tissue clamping mechanism spaced distally away from the elongated blade. The ultrasonic instrument has a pair of opposed jaws that are moveable from an open position to a closed position for compressing tissue therebetween. A central passageway extends longitudinally within the closed jaws for the passage of the elongated blade, and tissue is compressed laterally on either side of the advancing elongated blade. Examples of these types of ultrasonic surgical instruments can be found in U.S. patent application Ser. No. 6,004,335 by Vaitekunas et al. and in Japanese Unexamined Patent Application No. 9-253088 by Makoto Miyawaki et al.
Vaitekunas et al. teaches a surgical ultrasonic instrument that has a pair of flexible jaw members formed from a cantilever spring material. The flexible jaw members clamp upon tissue and are opened and closed by a conventional tube closure mechanism. A passageway or longitudinal slot is provided within each of the flexible jaws for the passage of an ultrasonic blade. A flat knife blade forms the distal end of the elongated blade and is aligned with the slots within the flexible jaws. The flat knife blade travels down the slots within the flexible jaw members cutting and coagulating the uncompressed tissue within the longitudinal slot.
The Makoto Miyawaki et al. surgical instrument has a pair of cantilever spring jaw beams extending from the distal end of the ultrasonic surgical instrument with rigid jaws extending from the jaw beams. The cantilever spring jaw beams are formed in a normally deflected open position and are opened and closed by a conventional tube closure mechanism. When closed, the rigid jaws clamp tissue laterally on opposite sides of the advancing blade. A narrow longitudinal passageway is provided between the rigid jaws for passage of the elongated blade.
Advancing the blade through the central within the passageway emulsifies or cuts the uncompressed portion of tissue directly in front of the blade, and coagulates tissue laterally to the moving blade. However, there is little lateral spread with these types of instruments and consequently, a narrow coagulation zone or tissue weld zone.
Tissue weld strength depends on two factors: compressing or clamping tissue at the weld site, and the surface area or size of the weld. Compressing the tissue sample before welding ensures the clamped tissue is homogeneous and all portions of the tissue are held in the desired configuration as the energy is applied. Assuming the tissue is properly compressed during welding, tissue weld strength will directly depend on surface area, i.e.: twice the weld area, twice the strength. Using the distal end of a blade member to cut and coagulate uncompressed tissue produces a narrow coagulation zone in uncompressed tissue, and a small tissue weld area.
Ultrasonic surgical instruments that use the side of the elongated blade to clamp produce a wide coagulation zone (caused by lateral thermal spread), however they lack the ability to clamp tissue laterally to the elongated blade. This reduces the potential strength of the tissue weld as portions of the coagulated tissue lie outside of the compressed tissue area, i.e.: outside of the tissue clamped between the clamp arm and the blade. Thus, tissue coagulated outside of the compressed tissue area is coagulated in an uncompressed condition, and weld strength suffers.
What is needed is an ultrasonic clamp and coagulation instrument that offers the advantages of all of the above ultrasonic surgical instruments by producing a wide tissue weld in compressed or clamped tissue. Therefore it would be advantageous to provide an ultrasonic surgical instrument that provides a substantially continuous pressure region that extends laterally on either side of the elongated blade member as well as against the side of the blade member, and can weld this substantially continuous pressure region with lateral thermal spread. Thus, this ultrasonic instrument can increase the size of the tissue weld by using lateral thermal spread to spread or expand the weld into adjacent compressed tissue, and into compressed tissue that is spaced laterally away from the elongated blade. In comparison, Vaitekunas et al. and Makoto Miyawaki et al. provide a non-continuous pressure region. They compress tissue laterally to both sides of the elongated blade, and provide uncompressed tissue in the path of the advancing elongated blade. Additionally, Vaitekunas et al. and Makoto Miyawaki et al. use the distal end of the elongated blade. This produces minimal coagulation or thermal effects in the uncompressed tissue and little or no effects to the laterally compressed tissue. Presently, there are no known ultrasonic surgical instruments or methods of use of such an instrument that can provide the surgeon with the improvements and benefits described above.
The present invention is a novel surgical method for increasing the size of a tissue weld in clamped tissue. The method, according to the present invention includes providing an end effector for an ultrasonic surgical instrument. The end effector includes an ultrasonic blade having a proximal and a distal end and a clamping mechanism having a clamping surface positioned opposite the ultrasonic blade. The clamping mechanism is adapted to clamp tissue against a side of the ultrasonic blade. A first support surface is positioned laterally on a first side of the ultrasonic blade, the first support surface being ultrasonically isolated from the blade and positioned opposite at least a portion of the clamping surface. A second support surface is positioned laterally on a second side of the ultrasonic blade, the second support surface also being ultrasonically isolated from the blade and positioned opposite at least a portion of the clamping surface.
Next, the clamping mechanism is actuated to clamp tissue between the clamping surface and the ultrasonic blade and between the clamping surface and the first and second tissue support surfaces. The clamped tissue defining a substantially continuous pressure region.
Finally, ultrasonic energy is applied to the ultrasonic blade for the creation of a tissue weld in the substantially continuous pressure region. The tissue weld spreads from tissue clamped between the clamping surface and the ultrasonic blade and into tissue clamped between the clamping surface and the first and second tissue support surfaces.
An alternate surgical method for increasing the size of a tissue weld in compressed tissue is disclosed. The alternate method comprises the following steps:
First, providing an end effector for an ultrasonic surgical instrument, the end effector including an ultrasonic blade having a proximal and a distal end and a clamping mechanism having a clamping surface positioned opposite the ultrasonic blade. The clamping mechanism is adapted to clamp tissue against the ultrasonic blade. A first support surface is positioned laterally on a first side of the ultrasonic blade, the first support surface being ultrasonically isolated from the blade and positioned opposite at least a portion of the clamping surface. The first support surface also having a support surface angle relative to the longitudinal axis of the ultrasonic blade. A second support surface is positioned laterally on a second side of the ultrasonic blade, the second support surface being ultrasonically isolated from the blade and positioned opposite at least a portion of the clamping surface. The second support surface also having generally the same support surface angle as the first support surface;
Second, the clamping mechanism is moved to a first position to clamp tissue between the clamping surface and the first and second support surfaces. The clamped tissue is spaced away from the ultrasonic blade and has an uncompressed tissue region positioned opposite the blade.
Third, the clamping mechanism is moved to a second position to clamp the uncompressed tissue region against the ultrasonic blade to create a substantially continuous pressure region within the tissue clamped within the end effector.
Last, applying ultrasonic energy to the clamped tissue in contact with the ultrasonic blade to create a tissue weld, the tissue weld spreading away from the clamped tissue in contact with the ultrasonic blade and into clamped tissue adjacent to and spaced away from the ultrasonic blade.
Additionally, yet another alternate surgical method for increasing the size of a tissue weld in compressed tissue is disclosed. The alternate method comprises the following steps:
First, providing an end effector for an ultrasonic surgical instrument, the end effector including an ultrasonic blade having a proximal and a distal end and a clamping mechanism having a clamping surface positioned opposite the ultrasonic blade. The clamping mechanism is adapted to clamp tissue against the ultrasonic blade. A first support surface positioned laterally on a first side of the ultrasonic blade, the first support surface being ultrasonically isolated from the blade and positioned opposite at least a portion of the clamping surface. The first support surface also has a support surface angle relative to the longitudinal axis of the ultrasonic blade. A second support surface positioned laterally on a second side of the ultrasonic blade, the second support surface being ultrasonically isolated from the blade and positioned opposite at least a portion of the clamping surface. The second support surface has generally the same support surface angle as the first support surface.
Second, the clamping mechanism is moved to a first position to clamp tissue between the clamping surface and the first and second support surfaces. The clamped tissue is spaced away from the ultrasonic blade and the tissue has an uncompressed tissue region opposite the blade.
Third, the ultrasonic blade is activated.
And last, the clamping mechanism is moved to a second position to clamp tissue against the active ultrasonic blade to create a tissue weld within the substantially continuous pressure region.